add mailmap to avoid dup of authors
add mailmap to avoid dup of authors

This change improves authors list of the project

Change-Id: I44c4cde077c071de3582d93b367110a792188962

froyobin/ceilometer,idegtiarov/ceilometer,pkilambi/ceilometer,m1093782566/openstack_org_ceilometer,pczerkas/aodh,isyippee/ceilometer,redhat-openstack/ceilometer,openstack/ceilometer,pkilambi/ceilometer,r-mibu/ceilometer,openstack/aodh,idegtiarov/ceilometer,MisterPup/Ceilometer-Juno-Extension,Juniper/ceilometer,sileht/aodh,mathslinux/ceilometer,ityaptin/ceilometer,maestro-hybrid-cloud/ceilometer,froyobin/ceilometer,maestro-hybrid-cloud/ceilometer,pczerkas/aodh,eayunstack/ceilometer,openstack/aodh,eayunstack/ceilometer,r-mibu/ceilometer,chungg/aodh,chungg/aodh,sileht/aodh,redhat-openstack/ceilometer,cernops/ceilometer,openstack/ceilometer,fabian4/ceilometer,fabian4/ceilometer,Juniper/ceilometer,mathslinux/ceilometer,ityaptin/ceilometer,cernops/ceilometer,isyippee/ceilometer,MisterPup/Ceilometer-Juno-Extension,m1093782566/openstack_org_ceilometer